M25.00

Intra-articular hemorrhage at a joint site that has not been identified or documented by the treating provider.

Verified May 8, 2026 · 5 sources ↓

Status: Billable
Chapter: 13
Related CPT: 9
Region: General

Drawn from CDCCMSAAOSAAPCICD

Documentation tips

What should appear in the chart to support M25.00.

Source · Editorial brief grounded in 5 cited references ↓

Record the specific joint by name in every encounter note — 'right knee hemarthrosis' versus 'joint hemarthrosis, unspecified' is the difference between a reimbursable specific code and an audit flag.
Document the etiology: traumatic (including mechanism), post-procedural, or spontaneous/coagulopathy-related — this determines whether an external cause code or S-code should accompany M25.00.
If joint aspiration was performed, note the gross appearance of aspirated fluid (bloody/sanguineous) — this is the strongest clinical validator for a hemarthrosis diagnosis.
When imaging is obtained (MRI, X-ray), reference the specific finding that supports hemarthrosis (e.g., joint effusion with blood signal on MRI, fat-fluid level on plain film after trauma).
If hemarthrosis is a complication of anticoagulation therapy or hemophilia, document the underlying condition separately so the coder can assign the correct secondary or primary diagnosis code.

Related CPT procedures

Procedure codes commonly billed with M25.00. Linking the right diagnosis to the right procedure is what establishes medical necessity.

Source · CMS LCDs · AAOS specialty guidance · claims-pattern analysis

20600 $56.11

Needle aspiration and/or injection of a small joint or bursa — such as a finger or toe joint — performed without ultrasound guidance.

20604 $87.18

Arthrocentesis, aspiration and/or injection of a small joint or bursa (e.g., fingers, toes) performed with ultrasound guidance, including permanent image recording and reporting.

20610 $68.81

Aspiration and/or injection of a major joint or bursa (shoulder, hip, knee, or subacromial bursa) performed without ultrasound guidance.

20611 $104.21

Aspiration or injection of a major joint or bursa performed under real-time ultrasound guidance, with permanent image documentation.

27310 $689.06

Open arthrotomy of the knee for exploration, drainage of infection, or removal of a foreign body or loose material from the joint space.

29871 $491.33

Arthroscopic surgical procedure on the knee performed specifically to treat infection, including joint lavage (washout) and drainage of infected material.

73221 $205.08

MRI of any upper extremity joint — shoulder, elbow, or wrist — performed without contrast material.

73721 $204.41

MRI of a lower extremity joint (hip, knee, or ankle) performed without contrast material.

27370 View procedure details

Common coding pitfalls

The recurring mistakes coders make with M25.00 and adjacent codes.

Source · Editorial brief grounded in CDC ICD-10-CM tabular guidance, AAOS coding references, and cited references ↓

Using M25.00 when the joint IS documented — any identified joint has a more specific M25.0x code; M25.00 is never appropriate when laterality and joint site are known.
Failing to sequence a current injury S-code first when hemarthrosis is the direct result of acute trauma — M25.00 should not lead when a specific traumatic injury code better captures the encounter.
Omitting an external cause code when the hemarthrosis has an identifiable cause; the Tabular instructs an additional external cause code when applicable.
Confusing hemarthrosis with general joint effusion — hemarthrosis is specifically blood in the joint; code M25.40-series covers non-hemorrhagic effusion and is not interchangeable.
Appending a 7th character to M25.00 — M-codes in Chapter 13 do not use the A/D/S encounter extensions that apply to injury S-codes.

Clinical context

Source · Editorial summary grounded in 5 cited references ↓

M25.00 is the last-resort code in the M25.0 hemarthrosis family — use it only when the operative note, imaging report, or clinical documentation genuinely fails to identify which joint is bleeding. Hemarthrosis arises from trauma (ligament tears, fractures, post-procedural bleeding) or spontaneously in patients with coagulopathies such as hemophilia. In an orthopedic setting, traumatic hemarthrosis is far more common, and the joint is almost always identifiable from the mechanism and physical exam.

Before assigning M25.00, work through the full M25.0 hierarchy. If the knee is involved, use M25.061 (right) or M25.062 (left). If the shoulder, use M25.011/M25.012. Specific lateralized codes exist for elbow, wrist, hip, ankle, and other joints. M25.00 is appropriate only when the provider has genuinely not documented which joint is affected — for example, a consult note where the joint is still under evaluation or the record is incomplete.

When hemarthrosis results from an identified external cause (e.g., traumatic injury, anticoagulant adverse effect), the ICD-10-CM Tabular instructs coders to append an external cause code. If a current injury code (S-code) better captures the hemarthrosis as part of the acute trauma, sequence the S-code first and use M25.00 only for chronic or non-traumatic presentations without a more specific injury code. Payers increasingly scrutinize unspecified joint codes; expect documentation requests or medical necessity reviews on claims coded to M25.00 without accompanying specificity.

Sibling codes

Other billable codes under M25.0 (laterality / anatomic variants).

M25.08

Hemarthrosis, other specified site

Frequently asked questions

Source · Generated from the editorial pipeline, verified against 5 cited references ↓

01When is M25.00 actually appropriate versus a more specific hemarthrosis code?

M25.00 is appropriate only when the treating provider has not identified or documented which joint is involved. If any joint site is documented — even without laterality — use the joint-specific unspecified-side code (e.g., M25.069 for unspecified knee) rather than M25.00.

02Should M25.00 be sequenced first when hemarthrosis follows acute trauma?

No. When hemarthrosis is the direct result of a documented acute injury, the relevant S-code for the traumatic injury typically leads. M25.00 (or the specific hemarthrosis code) may be used as an additional code if it adds clinical value beyond what the S-code already captures.

03Does M25.00 require an external cause code?

When the hemarthrosis has an identifiable external cause — such as a fall, sports injury, or adverse effect of anticoagulant therapy — ICD-10-CM instructs you to add an external cause code. If the cause is truly unknown, the external cause code is optional but still advisable for clean claim processing.

04Can M25.00 be used for hemophilia-related hemarthrosis?

It can, but the hemophilia code (e.g., D66, D67, or D68.x) should be sequenced as the principal or primary diagnosis, with M25.00 as a secondary code identifying the joint manifestation. If the specific joint is documented, use the lateralized hemarthrosis code instead of M25.00.

05Is M25.00 the same as a joint effusion code?

No. Hemarthrosis (M25.0x) specifically means blood in the joint space, confirmed by aspiration of bloody fluid or imaging findings consistent with hemorrhagic effusion. Non-hemorrhagic joint effusion is coded to M25.40-series. Do not use them interchangeably.

06Does M25.00 use 7th-character extensions like injury codes do?

No. M25.00 is a Chapter 13 musculoskeletal code and does not take 7th-character encounter extensions (A/D/S). Those extensions apply to injury codes in Chapters 19–20 (S- and T-codes).

07What CPT procedures are commonly billed alongside M25.00?

Arthrocentesis (20600, 20604, 20610, 20611) is the most common procedural pairing when the hemarthrosis is aspirated for diagnosis or relief. Arthroscopy codes and imaging (MRI, X-ray) may also appear on the same claim depending on the workup performed.

Sources & references

Editorial content was developed using the following public sources. Last verified May 8, 2026.

01CDC ICD-10-CM Tabular List 2026 — https://www.icd10data.com/ICD10CM/Codes/M00-M99/M20-M25/M25-/M25.00
02CMS ICD-10-CM Official Guidelines for Coding and Reporting FY2025 — https://www.cms.gov/files/document/fy-2025-icd-10-cm-coding-guidelines.pdf
03AAOS Resident Guide ICD-10 — https://www.aaos.org/globalassets/quality-and-practice-resources/coding-and-reimbursement/resident-guide/resident-guide_icd10.pdf
04AAPC Codify M25.00 — https://www.aapc.com/codes/icd-10-codes/M25.00
05ICDcodes.ai Hemarthrosis Documentation — https://icdcodes.ai/diagnosis/hemarthrosis/documentation

Mira AI Scribe

The Mira AI Scribe captures the specific joint name and side, the nature of the fluid on aspiration or imaging, the mechanism of injury or underlying coagulopathy, and any prior treatment such as aspiration or arthroscopy. That documentation lets the coder step down from M25.00 to a lateralized, joint-specific code — preventing payer downcoding, medical necessity denials, and compliance exposure from overuse of unspecified codes.

See how Mira captures M25.00 documentation